The Onchain Core Data API provides public-chain summaries, blocks, transactions, event logs, and address data. Always discover support for the target endpoint before calling it. Support for a chain in one module does not imply support in another module.

API references#

Quick start#

Request conventions#

• Base URL: https://web3.okx.com
• chainIndex is a numeric string, such as 1 for Ethereum and 0 for Bitcoin. Chain names are not accepted.
• Time parameters use Unix timestamps in milliseconds, such as 1597026383085.
• Every request requires OK-ACCESS-KEY, OK-ACCESS-SIGN, OK-ACCESS-TIMESTAMP, and OK-ACCESS-PASSPHRASE.
• Generate the signature from the method, path, query, body, and timestamp of the current request. Do not reuse it across URLs or pages.
• Successful responses use a code, msg, and data envelope. code is a string.

Recommended request flow#

1. Convert the input chain name to a chainIndex.
2. Call the target module's supported-chains endpoint.
3. Match both apiName and chainIndex in the response.
4. Call the target endpoint only after a match; otherwise return that the endpoint does not currently support the chain.
5. Split batch parameters and block ranges according to endpoint limits.
6. Return each cursor unchanged until the response cursor is an empty string.

Composed scenarios#

Supported-chain mapping#

Discover support by module#

Store the response as a supported[(module, apiName, chainIndex)] = true set. For example, before calling /api/v6/explorer/transaction/transaction-multi, check supported[("transaction", "transaction-multi", "1")].

apiName-to-endpoint mapping#

Use address/information-evm, event-log endpoints, and endpoints marked EVM-only only after the relevant support response confirms the chain. On 50038, refresh support for the current module instead of permanently marking the chain as globally unsupported. See the appendix for the complete name mapping.

Pagination, batches, and ranges#

Cursor pagination#

1. Omit cursor on the first request.
2. Pass the returned cursor unchanged on the next request; do not convert it to a page number.
3. Stop when cursor is an empty string.
4. For log endpoints, continue when logList is empty but cursor is non-empty.
5. Paginate serially within one cursor chain. Independent queries can run concurrently within the rate-limit budget.

Request limits#

Split oversized input on the client. Deduplicate merged results by transaction hash, log index, or another documented business key.

Appendix: complete chainName-to-chainIndex mapping#

Use this table to convert a chain name or alias to a candidate chainIndex. It includes mainnets, testnets, and historical names. It is not an endpoint-support list; before making a business request, match both apiName and chainIndex through the corresponding module's supported-chains endpoint.

Some names identify different networks or historical registry entries, including CORE=70000025 and CORE_EVM=1116, CRO=25 and CRO_COSMOS=394, and CFX=1030 and Conflux=503. Resolve ambiguous names from the network context instead of guessing from the display name alone.